When cutting off a product work sheet from a material work sheet in a continuous hole opening process by a turret punch press, a part of the outer circumference is left uncut and connected to the material work sheet. The connected part is cut off thereafter. By leaving a connected part likewise, in the punch processing, the work sheet feeding by a work holder which carries out feeding operation by gripping the edge of the material work sheet, can be carried out.
For example, the cutting off operation of the connected part is carried out by a subhead of which is a punch processing head exclusive for the cutting off operation, employed at a position apart from the turret. The discharging of the cut off product work sheet is generally carried out by a suction typed unloader. Since the small article cannot be sucked, a work chute to be mentioned in the following is to be used. The work chute is leading to the outside of the machine from the opening near the subhead in the upper surface of the table. The opening is closed during the processing.
Since the subhead is required to be located at a position apart from the turret, the subhead is to be located greatly off set from the main punch head provided in the designated position over the turret. As a result, it is difficult to obtain processing precision, the cutting off processing of the connected part of the product work sheet and the material work sheet cannot be carried out neatly, thus there are cases in which the quality of the product is influenced. Moreover, since the subhead is provided with the punch driving mechanism, by providing a subhead, the structure of the turret punch press becomes complicated and the cost is increased.
The object of the present invention is to provide a turret punch press capable of solving such problems, and capable of discharging easily the small article work sheet cut off from the material work sheet, without employing a separate subhead from a punch driving mechanism.